Fixes view reusing after animations
Added PSTCollectionElementCategory and exposed layoutAttributesForSupplementaryViewOfKind:atIndexPath: for subclassing layouts
Implement Decoration views
Reuse decoration views after animation
Merge pull request #250 from kgn/master

PSTCollectionElementCategory and layout subclassing
Merge pull request #252 from cysp/for-review/decoration-views

Implement Decoration views
Merge remote-tracking branch 'upstream/master'